Sample analysis can be performed by optically analyzing the reaction liquid obtained from the sample and a reagent reacting thereupon. For performing such an analysis, an analytical tool to provide a reaction field is mounted to an analyzing device that constitutes an optical system in which light emission and light reception are possible (See JP-A-8-114539, for example). In this case, to reduce the analysis error and improve the reliability of the analysis results, it is preferable to adjust the temperature of the analytical tool (particularly, the reaction solution) so that the sample reacts with the reagent at a generally constant temperature for each measurement. Particularly, in a system which utilizes enzyme reaction, the reaction speed largely depends on temperature. Therefore, the temperature of this system is controlled to e.g. ±0.1° C. relative to a prescribed target temperature.
FIG. 9A shows an example of method for adjusting temperature of a reaction solution. In this method, an analytical tool 9 is held on a heat block 91 having a heat capacity larger than that of a reaction solution 90, and the temperature of the heat block 91 is controlled for adjusting the temperature of the reaction solution 90 See JP-A-9-189703 and JP-A-10-253536, for example). In this method, a temperature sensor 92 embedded in the heat block 91 monitors the temperature of the reaction solution 90. When the temperature of the reaction solution 90 drops below a predetermined value, the heat block 91 is heated for raising the temperature, whereby the temperature of the reaction solution 90 is raised via the heat block 91. FIG. 9B shows another method, in which an analytical tool 9 is held on a heating element 93 which has an excellent temperature-tracking property. In this method, the temperature of the reaction solution 90 is directly adjusted by the heating element 93 (See JP-A-9-304269, for example). In this method again, the heating element 93 is driven in accordance with the monitoring results of the temperature sensor 92, whereby the temperature of the reaction solution 90 is adjusted.
In the above temperature adjustment methods, it is necessary to heat the heat block 91 or to drive the heating element 93 in raising the temperature of the reaction solution 90, which disadvantageously leads to high power consumption. Further, when the amount of the liquid component 90 is small as is in a micro-device, pinpoint heating of the region where the reaction solution 90 is retained cannot be performed easily by the use of a heating medium such as the heat block 91 or the heating element 93. Therefore, to raise the temperature of the liquid component 90 with high response, the heating medium 91, 93 need be made considerably large as compared with the region whose temperature is to be raised (the region directly below the reaction solution 90 in the figure). Therefore, the amount of heat utilized for raising the temperature of the reaction solution 90 relative to the amount of heat conducted from the heating medium 91, 93 becomes small, and the energy cannot be utilized efficiently.
As noted above, prior art temperature adjustment methods have disadvantages such as high power consumption and inefficient energy utilization. Therefore, it is difficult to apply the prior art temperature adjustment methods to an analyzing device driven by an internal power source such as a small battery (like one widely used at home, for example). Even the application of such methods to a small analyzing device is possible, it is not practical because the operating time of the analyzing device is considerably shortened. Although shortening of the operating time may be prevented by increasing the capacity of the internal power source, such an increase hinders the size reduction of the analytical tool, whereby convenience in carrying is reduced. When electric power is to be supplied from an external power source, an adapter for connecting the analyzing device to the external power source is necessary, which reduces the convenience in carrying and hinders the use when away from home.